There are numerous methods known in the prior art for making a threaded hole in metallic material. There are, however, several disadvantages to many of these methods employed by the prior art. For example, typically a hard metal tap is used to form threads in a hole. This requires a full set of taps for tapping various size holes. To relieve this problem of needing a full set of taps, the prior art has developed a series of special tapping screws. These special tapping screws have specific configurations which enable them to tap a hole. However, this requires purchase of special screws, which are more expensive than ordinary screws, to tap a hole. Other prior art methods use a specially configured hole which is costly and time-consuming to form.
Examples of these prior art devices are disclosed in U.S. Pat. Nos. 1,909,476 to Trotter; 1,963,542 to Bergstrom; 2,113,600 to Olson; 3,491,974 to Swanquist; 3,575,313 to Trachtenberg et al; 3,701,837 to Fork; 4,000,874 to Finley et al; 4,472,097 to Keifer et al; 4,580,689 to Slater; 4,637,185 to Bowman; 4,666,055 to Lewis; and 4,706,831 to Williams, Jr. Also, when using metric taps, the Standard Handbook of Fastening and Joining by Robert O. Parmley, Copyright 1977, by McGraw-Hill, Inc., Section 16, page 16-25, discloses a formula for determining the diameter of the hole to be drilled when using a metric tap.
In view of the above, it is apparent that there exists a need for a way to tap a hole in metallic material without any special equipment. This invention addresses this need in the art, along with other needs which will become apparent to those skilled in the art once given this disclosure.